航空发动机带凸肩风扇转子叶片裂纹产生原因

Cause of Crack in Rotor Blade of Aero-Engine Shouldered Fan

某航空发动机TC4合金风扇转子叶片凸肩根部转接部位过早产生裂纹,通过宏观形貌观察、断口分析以及接触放电试验,分析了裂纹产生原因。结果表明:失效风扇转子叶片裂纹为疲劳裂纹,裂纹萌生于叶片叶盆侧凸肩根部至排气边的转接区域表面;在叶片凸肩耐磨层钎焊过程中,感应线圈靠近或接触叶片基体而发生接触放电,导致叶片基体局部熔化烧伤和阻流剂熔化,是叶片萌生疲劳裂纹的原因。建议采用绝缘胶布对感应线圈进行绝缘处理,选取合适的感应电流和焊接距离,以防止线圈与叶片之间发生接触放电。

Cracks were produced prematurely in the transition area of the shoulder root of TC4 alloy fan rotor blade of an aero-engine.The cause of the cracks was studied through macromorphology observation,fracture analysis and contact discharge test.The results show that the cracks of the failed fan rotor blades were fatigue cracks,and initiated on the surface of the transition area from the root of the leaf pot side shoulder to the exhaust edge.The induction coil closed or contacted the blade substrate and contact discharge occurred,resulting in local melting and burning of the blade substrate and melting of the flow blocking agent during the brazing process of the wear-resistant layer of the blade shoulder,which was the cause of fatigue crack initiation of the blade.It was suggested that insulating the induction coil by insulating tape and using an appropriate induction current and welding distance to prevent contact discharge between the coil and the blade.